The present invention relates to an electronic apparatus such as a computer, and in particular to a forced-air cooled electronic apparatus.
An electronic apparatus such as a computer houses a plurality of heat emitting semiconductor devices. Cooling these semiconductor devices is a requirement to get electronic performance from them. In its typical cooling method, the electronic apparatus is provided with a fan or blower within the cabinet of the apparatus to force external air to circulate within the cabinet.
Since cool external air is let in into the cabinet and then forced to circulate within the cabinet to cool the apparatus, the fed air can be moist air having some content of moisture. When the air has a relatively high moisture content, the cabinet suffers condensation. Condensation possibly causes the circuitry of the apparatus to short, leading to a fault such as the malfunction of the circuitry of the apparatus. If a semiconductor itself or printed circuit board suffers condensation, the risk of fault is more likely.
According to Japanese Patent Unexamined Publications No. 59-79599, No. 1-236699 and No. 3-252199, electronics are housed in a sealed container and dehumidifier means is used to lower humidity inside the container to prevent condensation. However, these prior art techniques are related to condensation prevention inside the sealed containers, where only mild condensation is expected. The prior art gives practically no consideration to condensation prevention in the forced air cooling method in which external cool air is taken in into the cabinet to cool the apparatus.
One prior art condensation prevention technique in the forced air cooling system has been disclosed by Japanese Patent Unexamined Publication No. 4-294597. According to this disclosure, a fan which is switched on at power-on of its host electronic apparatus circulates air. During power-off, the electronic apparatus is sealed in a container to prevent condensation and a hygroscopic compound such as silica gel is used to dehumidify the interior of the container. The fan is switched back on to take external air in. Circulated air that has exchanged heat with electronics is applied to the hygroscopic compound to recover its hygroscopicity performance.
Although the above prior art can prevent condensation during power-off, it gives no consideration to condensation that takes place during forced air cooling period.
It is an object of the present invention to prevent condensation during forced air cooling period.